Articulating drill with integrated circuit board and method of operation

ABSTRACT

The present invention is an articulating hand power tool with a main housing having a longitudinal axis, a head portion rotatably engaged with the main housing for placement at a plurality of angles with respect to the longitudinal axis of the main housing, an integrated circuit board located within the main housing and at least one controller accessible from outside of the main housing for controlling the integrated circuit board.

This application claims the benefit of provisional U.S. patentapplication Ser. No. 60/733,546, filed on Nov. 4, 2005. The disclosureof this provisional patent application is hereby totally incorporated byreference in its entirety.

FIELD OF THE INVENTION

The present invention relates to an electric hand tool and moreparticularly to an articulating power hand tool.

BACKGROUND

Power tools including battery operated tools are well-known. These toolstypically include an electric motor having an output shaft that iscoupled to a spindle for holding a tool. The tool may be a drill bit,sanding disc, a de-burring implement, or the like. The power source maybe a battery source such as a Ni-Cad or other rechargeable battery thatmay be de-coupled from the tool to charge the battery and coupled to thetool to provide power.

The power source is coupled to the electric motor through a powerswitch. The switch includes input electrical contacts for coupling theswitch to the power source. Within the switch housing, a moveablemember, sometimes called a switch, is coupled to the input electricalcontacts and to a wiper of a potentiometer. As the moveable member ispressed against the biasing component of the switch, it causes the inputelectrical contacts to close and provide current to one terminal of theelectric motor and to the wiper of the potentiometer. The moveablemember is biased so that the biasing force returns the moveable memberto the position where the input electrical contacts are open when themoveable member is released. The current is coupled to a timing signalgenerator, such as a 555 circuit, through the potentiometer. As themember or trigger continues to be pulled against the biasing force sothat the wiper reduces the resistance of the potentiometer from an opencircuit to a low resistance or short circuit condition, the level of thecurrent supplied to the timing signal generator increases.

The output of the timing signal generator is coupled to the gate of asolid state device, such as a MOSFET. The source and drain of the solidstate device are coupled between a second terminal of the electric motorand electrical ground. In response to the timing signal turning thesolid state device on and off, the motor is selectively coupled toelectrical ground through the solid state device. Thus, as the timingsignal enables the solid state device to couple the motor to electricalground for longer and longer intervals, the current flows through themotor for longer intervals. The longer the motor is coupled to power,the faster the electric motor rotates the output shaft of the motor.Consequently, the tool operator is able to vary the speed of the motorand, correspondingly, the rotational speed of the tool in the spindle bymanipulating the trigger for the power switch.

The timing signal generated by the timing circuit selectively couplesthe motor to the power source because it alternates between a logicallyon-state and a logically off-state. During the logically off-state, themotor is no longer coupled to the power source. The windings in themotor, however, still have current in them. To provide a path for thiscurrent, a freewheeling diode is provided across the terminals of themotor.

The trigger of the power switch is also coupled to two sets of contacts.One of these contact sets is called the bypass contact set. When thetrigger reaches the stop position of its travel against the biasingcomponent, it causes the bypass contacts to close. The closing of thebypass contacts causes the current through the motor to bypass the solidstate device and be shunted to electrical ground. This action enablesthe motor to remain continuously coupled to the power source and reachits maximum speed.

The other set of electrical contacts controlled by the switch triggerare the brake contacts. These contacts are closed when the trigger is atthe fully biased off position. As the trigger is moved against thebiasing force, the brake contacts open. The brake contacts couple oneterminal of the electric motor to the other terminal of the motor. Inresponse to the trigger being released from a position that enablespower to be supplied to the motor, the brake contacts close to provide acurrent path through the motor for dynamic braking of the motor. Thisenables the motor to stop more quickly than if the motor simply coastedto a stop under the effects of friction.

While the power switch described above is effective for tool speedcontrol, it suffers from some limitations. Known power switches arelimited because of the effect of carrying the battery current throughthe switch. When the battery current is first applied to the contacts,the current level may be sufficient to cause arcing. Arcing may causethe contacts to become pitted or otherwise damaged. Additionally, largecurrents also tend to heat the components within the switch.Consequently, the switch may require a heat sink or a larger volume todissipate heat within the switch. The larger size of the housing for theswitch may also impact the design of the tool housing to accommodate theswitch geometry. Another factor affecting the geometry or size of theswitch housing is the potentiometer that generates the variable speedsignal. Typically, the distance traveled by the wiper of thepotentiometer is approximately the same as the distance traveled by thetrigger. In many cases, this distance is approximately 7 mm and thisdistance must be accommodated by the potentiometer and the housing inwhich the potentiometer is mounted.

The direction of motor rotation depends upon whether the battery currentflows through the motor from the first terminal to the second terminalor vice versa. Because bidirectional rotation of battery operated toolsis desirable, most tools are provided with a two position switch thatdetermines the direction of battery current through the electric motor.In some previously known switches for battery operated tools, this twoposition switch is incorporated in its own housing that is mounted tothe switch housing. The additional two position switch housing mayexacerbate the space issues already noted. In other known switches, thetwo position switch may be integrated within the switch housing. Thisarrangement, while perhaps smaller than the two housing construction,adds another set of contacts to the switch with the attendant heat orcontact deterioration concerns that arise from the motor current flowingthrough these contacts.

Another limitation of known power switches relates to the torque controlfor power tools. In some battery operated tools, mechanical clutches areused to set a torque limit for the tool. When the resistance to therotation of the tool causes the torque generated by the tool to increaseto the torque limit, the clutch slips to reduce the torque. The torquemay then build again until it reaches the limit and the clutch slipsagain. The iterating action of clutch slippage followed by renewedtorque buildup is sensed by the operator as vibration. This vibrationinforms the operator that the tool is operating at the set torque limit.This slippage also causes wear of the mechanical components fromfriction and impact.

Electric drills suffer the foregoing limitations. Moreover, electricdrills are usually constructed as straight-drilling machines in whichthe drill spindle extends parallel to the motor shaft and axis of thehousing and, for specific purposes, as angular-drilling machines inwhich the drill spindle is aligned at a right angle to the motor shaftand housing axis. In certain applications in which both straight andangular drilling must be carried out, as is the case in installations inwooden house construction, the two machines must be at hand forcontinuous alternation.

What is needed is an articulating power hand tool which does not requirea large housing for mechanical switches. What is further needed is anarticulating power hand tool with a reduced forward section and acompact articulating system to allow for use of the tool in confinedareas.

SUMMARY

The present invention is an articulating hand power tool. In oneembodiment, the tool includes An articulating hand power tool with amain housing having a longitudinal axis, a head portion rotatablyengaged with the main housing for placement at a plurality of angleswith respect to the longitudinal axis of the main housing, an integratedcircuit board located within the main housing and at least onecontroller accessible from outside of the main housing for controllingthe integrated circuit board.

In another embodiment, a hand power tool includes a longitudinallyextending main housing, a head portion configured to be engaged with themain housing at a plurality of angles with respect to the longitudinalaxis of the main housing, each of the plurality of angles within asingle plane, an articulation gear system for providing motive force toa bit holder in the head portion including a motor side pinion gearhaving an axis of rotation generally parallel to a longitudinal axis ofthe housing and an output pinion gear having an axis of rotationgenerally parallel to a longitudinal axis of the head portion, whereinthe motor side pinion gear is operatively connected to the output sidepinion gear through a bevel gear, a controller operable from outside ofthe main housing and located generally on the plane and an integratedcircuit located within the main housing and responsive to thecontroller.

One method in accordance with the invention includes rotating a headportion of a power tool to one of a plurality of angles with respect tothe longitudinal axis of a main housing of the power tool, moving avariable speed trigger switch located outside of the main hosing,generating a variable speed signal with an integrated circuit locatedwithin the main housing in response to the movement of the variablespeed trigger, controlling the speed of a motor located within the mainhousing based upon the variable speed signal and transferring motiveforce from the motor to a component within the head portion.

These and other advantages and features of the present invention may bediscerned from reviewing the accompanying drawings and the detaileddescription of the preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may take form in various system and methodcomponents and arrangement of system and method components. The drawingsare only for purposes of illustrating exemplary embodiments and are notto be construed as limiting the invention.

FIG. 1 shows a perspective view of an articulating drill incorporatingfeatures of the present invention;

FIG. 2 shows a side elevational view of the articulating drill of FIG. 1with the rechargeable battery pack removed;

FIG. 3 shows a perspective view of the articulating drill of FIG. 1 withthe battery pack, a portion of the main housing cover, and a portion ofthe head housing removed and a bit in the bit holder;

FIG. 4 shows a cross-sectional view of the head portion, thearticulating gear system and the planetary gear system of thearticulating drill of FIG. 1;

FIG. 5 shows an exploded perspective view of the head portion, includingan automatic spindle lock system, of the articulating drill of FIG. 1;

FIG. 6 shows a top plan view of the head portion of the drill of FIG. 1with some components located within bays in the head housing;

FIG. 7 shows a top plan view of a bracket used to support an outputpinion shaft in the articulating drill of FIG. 1;

FIG. 8 shows a side plan view of the bracket of FIG. 7;

FIG. 9 shows a top elevational view of the planetary gear section,articulating section and head portion of the articulating drill of FIG.1 with the main housing and a portion of the head housing removed;

FIG. 10 shows a side elevational view of the articulating gear system ofthe articulating drill of FIG. 1 including a bevel gear and two piniongears;

FIG. 11 is a perspective view of a portion of the head housing of thedrill of FIG. 1 with a plurality of teeth in a well which are formedcomplimentary to teeth on the articulation button;

FIG. 12 shows a perspective view of the articulating button of thearticulating drill of FIG. 1;

FIG. 13 shows a perspective view of the bottom of the articulatingbutton of FIG. 12;

FIG. 14 shows a partial top elevational view of the inner surface of theouter housing of the articulating drill of FIG. 1 with teeth formedcomplimentary to the teeth on the articulation button and a hole forreceiving a raised portion of the articulating button;

FIG. 15 shows a top elevational view of the inner surface of the outerhousing of the articulating drill of FIG. 1;

FIG. 16 shows a partial plan view of the articulating drill of FIG. 1with the head portion aligned with the main housing portion and withouta dust lid;

FIG. 17 shows a partial plan view of the articulating drill of FIG. 1with the head portion aligned with the main housing portion with a dustlid;

FIG. 18 shows a side elevational view of the articulating drill of FIG.18 with the head portion rotated to an angle of 90 degrees from the mainhousing portion of the drill and a portion of the main housing portionremoved to show the position of the dust lid of FIG. 17;

FIG. 19 shows a side elevational view of the articulating drill of FIG.18 with the head portion rotated to an angle of 180 degrees from themain housing portion of the drill and a portion of the main housingportion removed to show the position of the dust lid of FIG. 17;

FIG. 20 shows a detail view of the dust lid of FIG. 19;

FIG. 21 shows a perspective view of the articulating drill of FIG. 1with the variable speed trigger switch, clutch control and a portion ofthe main housing removed;

FIGS. 22 a, 22 b and 22 c show various views of a printed circuit boardof the articulating drill of FIG. 1 in accordance with principles of theinvention;

FIG. 23 shows a perspective view of the articulating drill of FIG. 21with a collapsible boot with an internal reflective surface installedover a light generator and a light sensor;

FIG. 24 shows a schematic/block diagram of the drill of FIG. 1incorporating an optical switch for motor speed control;

FIG. 25 shows a side elevational view of a drill bit in the form of ascrew driver bit that may be used with the articulating drill of FIG. 1;

FIG. 26 shows a cross-sectional view of the drill bit of FIG. 25 beinginserted into the articulating drill of FIG. 1;

FIG. 27 shows a cross-sectional view of the drill bit of FIG. 25inserted into the articulating drill of FIG. 1;

FIG. 28 shows a partial top elevational view of a bevel gear inaccordance with principles of the invention with two pinion gears at a90 degree spacing;

FIG. 29 shows a partial top elevational view of the bevel gear of FIG.28 with the two pinion gears at a 180 degree spacing;

FIG. 30 shows an electrical diagram/schematic of a powered tool thatdynamically brakes the tool motor using a motor interface circuit havinga half bridge to provide vibratory feedback to the operator that thetorque limit has been reached;

FIG. 31 shows an electrical diagram/schematic of a circuit that may beused with the drill of FIG. 1 which dynamically brakes the drill motorusing a motor interface circuit having a full H-bridge circuit toprovide vibratory feedback to the operator that the torque limit hasbeen reached; and

FIGS. 32A and 32B show an electrical diagram/schematic of a powered toolthat provides solid state motor speed control in correspondence with avariable speed signal from an optical switch and that dynamically brakesthe motor to indicate a torque limit has been reached.

DESCRIPTION

An articulating drill generally designated 100 is shown in FIG. 1. Inthe embodiment of FIG. 1, the drill 100 includes a main housing portion102 and a head portion 104. The main housing portion 102 houses a motorand associated electronics for control of the drill 100. The mainhousing portion 102 includes a battery receptacle for receiving arechargeable battery pack 106 as is known in the art. In one embodiment,the rechargeable battery pack 106 comprises a lithium-ion battery. Thebattery pack 106 is removed by depression of the battery release tabs108. FIG. 2 shows the drill 100 with the battery pack 106 removed. Thedrill 100 may alternatively be powered by an external power source suchas an external battery or a power cord.

A variable speed trigger switch 110 controls the speed at which themotor rotates. The direction of rotation of the motor is controlled by areversing button 112 which slides within a finger platform 114.Ventilation openings 116 allow for cooling air to be circulated aroundthe motor inside of the main housing 102. A clutch control 118 sets themaximum torque that may be generated when using the drill 100. At theposition shown in FIG. 1, the clutch control 118 is at the highestsetting or drill mode. At the highest setting, the clutch is disabled toprovide maximum torque. By sliding the clutch control 118 downwardlyfrom the position shown in FIG. 1, a user may set a desired torque limitthat is allowed to be generated by the drill 100 as discussed in moredetail below. Accordingly, at settings other than the highest setting, atorque above the setting of the clutch control 118 causes the clutch toactivate.

The main housing portion 102 also includes an articulation button 120and a plurality of angle reference indicators 122 molded onto the outersurface 124 of the main housing 102. In the embodiment of FIG. 1, thereare five angle reference indicators 122 used to identify five angularpositions in which the head portion 104 may be placed.

The head portion 104 includes a collet locking device 126 and an angleindicator 128. The angle at which the head portion 104 is positioned isindicated by the angle reference indicator 122 with which the angleindicator 128 is aligned. As shown in FIG. 1, the head portion 104 is ata 90 degree angle with respect to the main housing portion 102. In FIG.2, the head portion 104 is axially aligned with the main housing portion102. Although the embodiment of FIGS. 1 and 2 has five angle referenceindicators 122, there may be additional or fewer angle referenceindicators 122 and corresponding angles at which the head portion 104may be placed with respect to the main housing portion 102.

Referring now to FIGS. 3-6, the collet locking device 126 is locatedaround a bit holder 130 which is in turn supported by a ball bearing 132that is fixed within a bearing pocket 134 of the head housing 136. Thecollet locking device 126 includes a sleeve 138 with recesses 140. Aspring 142 is positioned about the bit holder 130. The bit holder 130includes a hole 144 which receives a cylinder pin 146 and recesses 148which receive steel balls 150.

The bearing 132 abuts the head housing 136 of the head portion 104 atthe outer rear periphery of the bearing 132. More specifically, thebearing 132 abuts a flange 152. In this embodiment, the flange 152 iscontinuous about the housing 136, although a flange may alternatively bein the form of a plurality of fins located about the inner portion ofthe housing 136.

The bit holder 130 is operably coupled to a drive collet 154 which is inturn connected to an output pinion shaft 156 through a drive plate 158which is fixedly attached to the output pinion shaft 156. A lock ring160 surrounds the drive collet 154 and three locking pins 162. The lockring 160, the drive collet 154, the drive plate 158, and the lockingpins 162 all comprise an automatic spindle lock system such that theoutput bit holder 130 can only be driven from the pinion side as knownin the art. When driven from the bit side, i.e., when the tool 100 isused as a manual screwdriver, the spindle lock system keeps the outputpinion shaft 156 from rotating thus facilitating use of the tool 100 asa manual screwdriver. In an alternative embodiment, a manuallymanipulated locking device may be used.

A pinion gear 164 is located at the opposite end of the output pinionshaft 156 from the drive plate 158. One end of the output pinion shaft156 is maintained in axial alignment by a bearing 166 which fits withinbearing pocket 168. The opposite end of the output pinion shaft 156 issupported by a sleeve 170. The sleeve 170 is supported on one side by aflange 172 on the head housing 136. On the opposite side, the sleeve 170is supported by a bracket 174 also shown in FIGS. 7 and 8.

The bracket 174 includes a support area 176 configured complimentary toa portion of the sleeve 170. Two connection arms 178 are configured tobe attached to the head housing 136 as shown in FIG. 9. The bracket 174eliminates the need to provide a matching flange for flange 172 moldedinto the opposite side of the head housing 136. The elimination of theneed for an opposing flange allows for a significant increase in designfreedom as the space requirements for the support structure for thesleeve 170 are reduced. The bracket 174 may be stamped from W108 steelto provide the needed rigidity and strength.

Referring now to FIG. 10, the pinion gear 164 forms a portion of anarticulating gear system 180. The articulating gear system 180 furtherincludes a bevel gear 182 which is engaged at the output portion of thearticulating gear system 180 with the pinion gear 164 and furtherengaged on the motor portion by pinion gear 184. The shaft 186 of thebevel gear 182 is supported at one end within a hole 188 (see FIG. 4) ofthe frame 190. The frame 190 is made from a zinc and aluminum alloyZA-8. This material provides a sufficiently low coefficient of frictionto ensure relatively small frictional forces exist between the shaft 186and the frame 190.

The shaft 186 is radially and axially supported at the opposite end by aball bearing 192 supported by the frame 190. At this end of the shaft186, however, comparatively larger forces are generated than at the endof the shaft 186 inserted within the hole 188. More specifically, asshown in FIG. 10, both pinion gear 164 and pinion gear 184 are locatedon the same side of the bevel gear 182. Accordingly, as the articulatinggear system 180 rotates, a force is generated on the bevel gear 182 inthe direction of the arrow 194 toward the base 196 of the bevel gear182. This force acts to disengage the bevel gear 182 from the piniongear 164 and the pinion gear 184. With this increased force acting uponthe bevel gear 182, an unacceptable amount of axial force would betransmitted to the bearing 192. Accordingly, a thrust bearing 198 isprovided to protect the ball bearing 192 and to provide a low frictionsupport for the base 196 of the bevel gear 182. The thrust bearing 198is made of a material with an acceptably low coefficient of frictionsuch as oil impregnated bronze commercially available from McMaster Carrof Chicago, Ill. Accordingly, the friction generated at the base 196 ofthe bevel gear 182 is maintained within acceptable levels.

Referring again to FIG. 4, the pinion gear 184 is fixedly attached to aplanetary gearbox shaft 200 which receives torque from a planetary gearsystem generally indicated as reference numeral 202. The planetary gearsystem 202 receives torque from a motor as is known in the art. Theplanetary gear system 202 is located within a planetary gear housing 204which is inserted partially within the frame 190. This arrangementallows for the planetary gear system 202 to be separately manufacturedfrom the other components while simplifying assembly of the planetarygear system 202 with the other components. This modularity furtherallows for alternative gearings to be provided in the planetary gearsystem 202 while ensuring a proper fit with the other components.

Generally, it may be desired to provide a simple friction fit betweenthe planetary gear housing 204 and the frame 190. In the embodiment ofFIG. 4, however, the articulating gear system 180 generates an axialforce along the planetary gearbox shaft 200. This axial force acts todisengage the planetary gear housing 204 from the frame 190.Accordingly, pins 206 and 208 which extend through both the planetarygear housing 204 and the frame 190 are provided. The pins 206 and 208ensure the planetary gear housing 204 does not become detached from theframe 190 during operation of the drill 100. Alternatively, theplanetary gear housing 204 and the frame 190 may be formed as anintegral unit.

Continuing with FIG. 4, the frame 190 is configured to slidingly matewith the head housing 136. To this end, the head housing 136 includes ashroud portion 210 which is complimentarily formed to the frame 190about the ball bearing 192. The head housing 136 further includes arecess 212 which is configured to receive the portion of the frame 190which defines the hole 188. Also shown in FIG. 4 is a well 214 whichincludes a plurality of teeth 216 shown in FIG. 11.

With further reference to FIGS. 12-14, the well teeth 216 are formedcomplimentary to a plurality of teeth 218 which are formed in thearticulation button 120. The articulation button 120 includes a raisedcenter portion 220 which is configured to fit within a hole 222 in themain housing portion 102. The teeth 218 of the articulation button 120are further configured to mesh with a plurality of teeth 224 formed onthe inner side of the main housing portion 102 around the hole 222. Thearticulation button 120 also includes a spring receiving well 226 on theside of the articulation button 120 facing the well 214. When assembled,a spring (not shown) is located within the well 214 and extends into thespring receiving well 226 forcing the raised center portion 220 of thearticulation button 120 toward a position wherein the articulationbutton 120 projects into the hole 222.

Referring to FIGS. 4 and 15, the frame 190 is supported axially in themain housing portion 102, which in this embodiment is made of plastic,by a rib 228. The rib 228 lies beneath a fin 230 of the frame 190 whenthe frame 190 is installed in the main housing portion 102 as shown inFIG. 3. The planetary gear system 202 is mechanically secured to a motor232 which is itself electrically connected to a printed circuit board234 which in turn is electrically connected to a battery contact holder236. The contact holder 236 mates with battery pack receptacles on thebattery pack 106 and transmits battery power to the electronic circuitboard 234 through lead wires (not shown). Another pair of lead wires(not shown) extend from the circuit board 234 to the motor terminals 238to deliver the required voltage level to the motor 232.

Referring now to FIG. 5, a gap 240 is provided in the portion of thehead housing 136 surrounding the bevel gear 182 which allows the headhousing 136 to be rotated with respect to the main housing portion 102while the pinion gear 164 remains engaged with the bevel gear 182. Whenthe head portion 104 is axially aligned with the main housing portion102, however, the gap 240 is exposed as shown in FIG. 16. Thearticulating gear system 180 is thus exposed allowing contaminantsaccess to the articulating gear system 180 which could foul thearticulating gear system as well as presenting a safety concern sinceclothing, fingers or hair could become enmeshed in the articulating gearsystem 180. Accordingly, a floating dust lid 242 shown in FIG. 17 isused to prevent contamination of the articulating gear system 180 and toavoid exposure of moving gears to an operator through the gap 240,particularly when the head housing 136 is axially aligned with the mainhousing portion 102 as shown in FIG. 17.

The dust lid 242 is located in a channel 244 defined by the main housingportion 102 and the head housing 136 as shown in FIGS. 18-20. Theposition of the dust lid 242 at the lower portion (as depicted in FIGS.18 and 19) of the channel 244 is constrained either by a movable dustlid travel limiter 246 positioned on the head housing 136, shown mostclearly in FIGS. 11 and 20, or by a portion 248 of the frame 190. Theposition of the dust lid 242 at the upper portion of the channel 244 isconstrained either by a neck portion 250 of the head housing 136 or by alip 252 in the main housing portion 102.

Referring now to FIGS. 3, and 21-23, the clutch control 118 ismechanically interfaced with a linear potentiometer 254 on the circuitboard 234. Also located on the circuit board 234 is a light sensor 256which is covered by a collapsible rubber boot 258 which is in turnmechanically fastened to the variable speed trigger 110. A reflectivesurface 260 (see FIG. 24) is located on the inside of the rubber boot258. A plastic spring locating member 262 which is mechanically securedto the circuit board 234 serves to locate and support a spring 264 whichis mechanically fastened to the variable speed trigger 110. The spring264 biases the variable speed trigger 110 in a direction away from thecircuit board 234 about a pivot 266. The circuit board 234 also containsa two position slide switch 268 which is mechanically interfaced to thereversing button 112.

Manipulation of the variable speed trigger 110 about the pivot 266changes the position of the reflective surface 260 relative to the lightsensor 256 to produce a variable speed control signal. While theembodiment of tool 100 incorporates an optical signal generator andreceiver for provision of a variable speed control signal, such a toolmay alternatively use a pressure transducer, a capacitive proximitysensor, or an inductive proximity sensor. In these alternativeembodiments, a pressure sensing switch for generating the variable motorspeed control signal may include a pressure transducer for generating avariable speed control signal that corresponds to a pressure applied tothe pressure transducer directly by the operator or through anintermediate member such as a moveable member that traverses thedistance between the stop position and the full speed position.

An embodiment of the variable motor speed control signal implementedwith a capacitive proximity sensor may include a capacitive sensor thatgenerates a variable speed control signal that corresponds to anelectrical capacitance generated by the proximity of an operator'sfinger or moveable member's surface to the capacitive sensor. Anembodiment implemented with an inductive proximity sensor generates avariable speed control signal that corresponds to an electricalinductance generated by the proximity of an operator's finger ormoveable member's surface to the inductive sensor.

Referring to FIG. 23, the variable speed control circuit 270 of the tool100 is schematically shown. The variable speed control circuit 270includes a power contact 272 which is operably connected to the variablespeed trigger switch 110. An optical signal generator 274 is coupled tothe battery 106 and arranged on the circuit board 232 such that lightemitted from the optical signal generator 274 is directed toward thereflective surface 260 of the variable speed trigger switch 110 anddirected toward the light sensor 256.

The light sensor 256 and the optical signal generator 274 may be locatedin the same housing or each may be within a separate housing. When thetwo components are located in the same housing, the light generator andsensor may emit and receive light through a single sight glass in thehousing. Alternatively, each component may have a separate sight glass.An integrated component having the light generator and sensor in asingle housing is a QRD1114 Reflective Object Sensor available fromFairchild Semiconductor of Sunnyvale, Calif. Such a housing issubstantially smaller than a potentiometer that has a wiper, whichtraverses approximately the same distance as the trigger traverses fromthe stop to the full speed position.

The optical signal generator 274 and the light sensor 256 may be aninfrared light emitter and an infrared light receiver. In an alternativeembodiment, an IR transceiver may be contained within a flexible dustcover that is mechanically fastened to the back of the variable speedtrigger switch. In such an embodiment, the inside of the cover in thevicinity of the moveable trigger reflects the optical signal to thereceiver for generating the speed control signal.

Control of a tool incorporating the light sensor 256 may be adverselyaffected by external energy sources such as the sun. Accordingly, in oneembodiment, the collapsible boot or dust cover 258 is made from anopaque material or coated with an opaque material such that energy fromthe sun which may leak past the housing and trigger arrangement does notaffect the signal received by the light sensor 256. Alternatively, alight sensor that is sensitive to a specific frequency band may be usedwith a device which shields the light sensor from only that specificfrequency band. In further embodiments, other circuitry or coding whichuniquely identifies the energy from the reflected signal frominterfering energy may be used.

The light sensor 256 is an optical transistor having a collector 276coupled to the battery pack 106 through the contact 272 and an emitter278 coupled to electrical ground though a voltage divider 280 and acapacitor 282. A timing signal generator 284 receives voltage from thevoltage divider 280. In the tool 100, the timing signal generator 264 isa commonly known 555 timer, although other timing signal generators maybe used.

The output of the timing signal generator 264 is coupled to a gate 286of a MOSFET 288 that has a drain 290 coupled to one of the motorterminals 238 and a source 292 coupled to electrical ground. The othermotor terminal 238 is coupled to the battery pack 106 through thecontact 272. A freewheeling diode 294 is coupled across the motorterminals 238. A bypass contact 296, which is operatively connected tothe variable speed trigger switch 110, is located in parallel to theMOSFET 288 between the motor terminal 238 and electrical ground and abrake contact 298 is in parallel with the freewheeling diode 294.

Operation of the drill 100 is explained with initial reference to FIGS.24-26. The collet locking device 126 is configured to operate with bitssuch as the screw driver bit 300 shown in FIG. 24. The screw driver bit300 and the bit holder 130 are complimentarily shaped. In this example,both the screw driver bit 300 and the bit holder 130 are generallyhexagonal in shape, although alternative shapes may be used. The screwdriver bit 300 has a diameter slightly less than the bit holder 130 sothat it may fit within the bit holder 130. The screw driver bit 300includes a notched area 302 and a tail portion 304.

Initially, the sleeve 138 is moved to the right from the position shownin FIG. 4 to the position shown in FIG. 26 thereby compressing thespring 142. As the sleeve 138 moves, recesses 140 in the sleeve 138 arepositioned adjacent to the recesses 148 in the bit holder 130. Then, asthe screw driver bit 300 is moved into the bit holder 130, the tailportion 304 forces the steel balls 150 toward the recesses 140 and outof the channel of the bit holder 130, allowing the tail portion 304 tomove completely past the steel balls 150.

At this point, the notched area 302 is aligned with the recesses 148.The sleeve 138 is then released, allowing the spring 142 to bias thesleeve 138 onto the bit holder 130 which is to the left from theposition shown in FIG. 27. As the sleeve 138 moves, the recesses 140 aremoved away from the recesses 148 thereby forcing the steel balls 150partially into the channel of the bit holder 130 as shown in FIG. 27.Movement of the steel balls 150 into the channel of the bit holder 130is allowed since the notched area 302 is aligned with the recesses 148.At this point, the bit 300 is firmly held within the bit holder 130.

The head housing 136 is then articulated to a desired angle with respectto the main housing portion 102. Initially, the spring (not shown) inthe spring receiving well 226 forces the articulation button 120 toextend into the hole 222. Accordingly, the teeth 218 of the articulationbutton 120 are meshed with the teeth 224 in the main housing portion 102as well as the teeth 216 in the well 214 of the head housing 136,thereby angularly locking the articulation button 120 (and the headhousing 136) with the main housing portion 102. Additionally, the dustlid 242 is constrained at the upper portion of the channel 244 by theneck portion 250 of the head housing 136 and at the lower portion of thechannel 244 by the portion 248 of the frame 190 as shown in FIG. 18.

The operator then applies force to the articulation button 120 causingthe spring (not shown) to be depressed thereby disengaging the teeth 218from the teeth 224. Thus, even though the teeth 218 remain engaged withthe teeth 216, the head portion 104 is allowed to pivot with respect tothe main housing portion 102. As the head portion 104 is articulated,for example, from the position shown in FIG. 1 to the position shown inFIG. 2, the pinion gear 164 articulates about the bevel gear 182. By wayof example, FIG. 28 shows the positions of the pinion gears 164 and 184with respect to the bevel gear 182 when the drill 100 is in theconfiguration shown in FIG. 1. In this configuration, the pinion gear164 is approximately 90 degrees away from the pinion gear 184 about theperimeter of the bevel gear 182. As the head portion 104 is articulatedin the direction of the arrow 306, the pinion gear 164 articulates aboutthe bevel gear 182 in the same direction. Thus, when the head portion104 is aligned with the main housing portion 102, the pinion gear 164 ispositioned on the bevel gear 182 at a location 180 degrees away from thepinion gear 184 as shown in FIG. 29.

Throughout this articulation, the pinion gears 164 and 184 remainengaged with the bevel gear 182. Accordingly, the bit holder 130 may berotated by the motor 232 as the head housing 136 is articulated.Additionally, the articulation of the head housing 136 causes themovable dust lid travel limiter 246 to contact the dust lid 242 and pushthe dust lid 242 along the channel 244. Thus, the dust lid 242, which isconfigured to be wider than the gap 240 as shown in FIG. 17, restrictsaccess from outside of the drill 100 to the articulating gear system180.

When the articulating drill 100 is rotated to the desired location, theoperator reduces the force applied to the articulating button 120. Thespring (not shown) in the spring receiving well 226 is then allowed toforce the articulation button 120 away from the well 214 until thearticulation button 120 extends through the hole 222. Accordingly, theteeth 218 of the articulation button 120 are meshed with the teeth 224in the main housing portion 102 as well as the teeth 216 in the well 214of the head housing 136, thereby angularly locking the articulationbutton 120 (and the head housing 136) with the main housing portion 102.

The desired direction of rotation for the bit 300 is then established byplacing the reversing button 112 in the position corresponding to thedesired direction of rotation in a known manner. Rotation isaccomplished by moving the variable speed trigger switch 110 about thepivot 266 to close the power contact 272. The closing of the contact 272completes a circuit allowing current to flow to the optical signalgenerator 274 causing light to be emitted.

The emitted light strikes the reflective surface 260 and a portion ofthe light is reflected toward the light sensor 256. The amount of lightreflected by the reflective surface 260 increases as the reflectivesurface 260 is moved closer to the light sensor 256. The increased lightsensed by the light sensor 256 causes increased current to be conductedby the light sensor 256 and the flow of current through the light sensor256 causes current to flow from the collector 276 to the emitter 278.Thus, as the intensity of the light impinging on the light sensor 256increases, the current conducted by the light sensor 256 increases. Thisincrease in current causes the voltage level presented by the voltagedivider 280 to the timing signal generator 284 to increase. Theincreased signal is the variable speed signal and it causes the timingsignal generator 284 to generate a timing signal in a known manner. Inthe depicted drill 100, the timing signal generator 284 is a commonlyknown 555 timer, although other timing signal generators may be used.

The timing signal generator 284 generates a timing pulse having alogical on-state that corresponds to the level of the variable speedsignal. This signal is presented to the gate 286 of the MOSFET 288. Whenthe signal present at the gate 286 is a logical on-state, the MOSFET 288couples one of the motor terminals 238 to ground while the other motorterminal 238 is coupled to battery power through the main contact 272.Thus, when the variable speed trigger switch 110 reaches a positionwhere the light sensor 256 begins to detect reflected light and generatea variable speed signal, the timing signal generator 284 begins togenerate a signal that causes the MOSFET 288 to couple one of the motorterminals 238 to ground. Once this occurs, current begins to flowthrough the MOSFET 288 and the motor 232 begins to rotate in thedirection selected by the reversing button 112.

The freewheeling diode 294 causes appropriate half-cycles of the currentin the windings of the motor 232 to flow out of the motor 232, throughthe diode 294, and back into the motor 232 when the MOSFET 288 does notconduct in response to the timing signal being in the off-state. Thisaction is known as freewheeling and is well known.

When the variable speed trigger 110 is in the full speed position, thetiming signal is predominantly in the on-state and the bypass contact296 closes. The closing of the bypass contact 296 enables the batterycurrent to continuously flow through the motor 232 so that the motor 232rotates at the highest speed.

When rotation is no longer desired, the operator releases the variablespeed trigger switch 110 and the spring 264 causes the variable speedtrigger switch 110 to rotate about the pivot 266 causing the bypasscontact 296 to open. Additionally, the brake contact 298 closes therebycoupling the motor terminals 238. The coupling of the two motorterminals 238 to one another through the brake contact 298 enablesdynamic braking of the motor.

The electronic control of the tool 100 thus requires less space for thecomponents that generate the variable speed signal than prior artcontrol systems. Because the distance traveled by the variable speedtrigger switch 110 does not have to be matched by the light signalgenerator 274 and the light sensor 256, considerable space efficiency isgained. Additionally, the light signal generator 274 and the lightsensor 256 do not require moving parts, so reliability is improved aswell. Advantageously, the light signal generator 274 and the lightsensor 256 may be mounted on the same printed circuit board 234 on whichthe timing signal generator 284 is mounted.

As the drill 100 is operated, the bit 300 is subjected to axial forces.The axial forces may result from, for example, pressure applied by theoperator or by an impact on the bit. In either instance, thearticulating gear system 180 is protected from damage without increasingthe bulk of the components within the articulating gear system 180. Thisis accomplished by directing axial forces from the bit 300 to the mainhousing portion 102 of the drill 100 while bypassing the articulatinggear system. With initial reference to FIG. 27, an impact on the bit 300tends to move the bit 300 further into the drill 100, or to the left asdepicted in FIG. 27. In prior art designs, not only could such a forcedamage the gear system, but the steel balls used to retain the bitwithin the bit holder would frequently jam necessitating replacement ofthe collet locking device.

As shown in FIG. 27, however, the cylinder pin 146 is positioned suchthat the tail portion 304 of the bit 300 will contact the cylinder pin146 before the wall of the notched area 302 contacts the steel balls150. Thus, an axial impact will not cause the steel balls 150 to jam. Ofcourse, the cylinder pin 146 must be made from a material sufficient towithstand the axial impact. In accordance with one embodiment, thecylinder pin 146 is made of AISI 4135 steel.

Referring now to FIG. 4, in the event of an axial impact, the force istransferred from the cylinder pin 146 to the to the bit holder 130. Theaxial force is transmitted from the bit holder 130 to the bearing 132which is located within the bearing pocket 134. Accordingly, the axialforce is transferred into the flange 152 (see also FIG. 5) of the headhousing 136. The head housing 136 in this embodiment is made fromaluminum alloy A380 so as to be capable of receiving the forcetransmitted by the bearing 132. The force is subsequently transferred tothe frame 190 and into the rib 228 of the main housing portion 102.

More specifically, two paths for the transfer of axial forces areprovided around the articulating gear system 180. The first pathpredominantly transfers axial forces when the head housing 136 isaxially aligned with the main housing portion 102. In thisconfiguration, axial forces pass from head housing 136 to the frame 190primarily through the recess 212 where the head housing 136 engages theframe 190 about the hole 188 (see FIG. 4) and at the shroud portion 210where the head housing 136 engages the frame 190 outwardly of the baseof the bevel gear 196.

The second path predominantly passes axial forces when the head housing136 is at a ninety degree angle with respect to the main housing portion102. In this configuration, axial forces are again transferred from thecylinder pin 146 to the to the bit holder 130. The axial forces thenpass primarily from the teeth 216 in the well 214 of the head housing136 to the teeth 218 on the articulation button 120 and then to theteeth 224 in the main housing portion.102.

When the head housing 136 is neither completely aligned with the mainhousing portion 102 or at a ninety degree angle with respect to the mainhousing portion 102, axial forces generally pass through both of theforegoing pathways. Accordingly, the effect of axial forces on thearticulating gear system 180 of the drill 100 are reduced. Because thearticulating gear system 180 is thus protected, the articulating gearsystem 180 may be constructed to be lighter than other articulating gearsystems.

In one embodiment, a printed circuit board which may be used in thedrill 100 or another power tool includes a circuit that providesvibratory feedback to the operator as shown in FIG. 30. The vibratoryfeedback circuit 308 includes a microcontroller 310, a driver circuit312, and motor interface circuit 314. The driver circuit 312 in thisembodiment is an integrated circuit that generates driving signals for ahalf-bridge circuit from a single pulse width modulated (PWM) signal, atorque limit indicating signal, which may be the same signal as the PWMsignal, and a motor direction control signal. The driver circuit 312 maybe a half bridge driver, such as an Allegro 3946, which is availablefrom Allegro Microsystems, Inc. of Worcester, Mass.

The output of the driver circuit 312 is connected to a motor 316 throughtwo transistors 318 and 320 which may be MOSFETs, although other typesof transistors may be used. The transistor 318 may be connected toeither terminal of the motor 316 through switches 322 and 324 while thetransistor 320 may be connected to either terminal of the motor 316through switches 326 and 328. A shunt resistor 330 is coupled betweenthe transistor 320 and electrical ground. The high potential side of theresistor 330 is coupled to the microcontroller 310 through an amplifier332. A power source 334 is also provided in the vibratory feedbackcircuit 308 and a maximum torque reference signal is provided from atorque reference source 336 which may be a linear potentiometer such asthe linear potentiometer 254.

The half-bridge control of the motor 316 eliminates the need for afreewheeling diode because the driver circuit 312 generates motorinterface circuit signals for selectively operating the motor interfacecircuit 314 to control the rotational speed of the motor 316. Morespecifically, a variable speed control signal 338, which may be from atrigger potentiometer or the like, is provided to the microcontroller310 for regulation of the rotation of the motor 316 by themicrocontroller 310. Based upon the variable speed control signal 338,the microcontroller 310 generates a PWM signal that is provided to thedriver circuit 312. In response to the PWM signal, the driver circuit312 turns transistors 318 and 320 on and off.

During typical operations, the transistor 318 is the complement of thetransistor 320 such that when the transistor 320 is on, the transistor318 is off. The rate at which the transistor 320 is turned on and offdetermines the speed of motor 316. The direction of rotation of themotor 316 is determined by the position of the switches 322, 324, 326and 328 under the control, for example, of a reversing switch.

The current through the motor 316 is provided through the transistor 320and the resistor 330 to electrical ground when the transistor 320 is inthe on-state. This current is related to the torque at which the motor316 is operating. Thus, the voltage at the high potential side of theresistor 330 is related to the torque on the motor 316. This motortorque signal is amplified by the amplifier 332 and provided to themicrocontroller 310. The microcontroller 310 compares the amplifiedmotor torque signal to the torque limit signal established by the torquereference source 336. The torque limit signal, which may alternativelybe provided by a different type of torque limit signal generator,provides a reference signal to the microcontroller 310 that correspondsto a current through the motor 316 that represents a maximum torquesetting for the motor 316.

In response to the microcontroller 310 receiving a motor torque signalthat exceeds the maximum torque setting for the motor 316, themicrocontroller 310 generates a braking signal that is provided to thedriver circuit 312. In response to the braking signal, the drivercircuit 312 turns transistor 320 to the off-state and leaves transistor318 in the on-state. This enables regenerative current to dynamicallybrake the rotation of the motor 316.

As dynamic braking occurs, the torque experienced by the motor 316decreases until the sensed torque is less than the maximum torquesetting for the motor 316. The microcontroller 310 then returns thetransistor 320 to the on-state, thereby rotating the motor 316 andincreasing the torque experienced by the motor 316. In this manner, themotor 316 alternates between rotating and dynamically braking whichcauses the tool to vibrate and alert the operator that the torque limithas been reached. An effective frequency for providing this vibratoryfeedback is 30 Hz. The torque limit indicating signal that results inthis operation continues as long as the trigger remains depressed.Alternatively, the microcontroller may be programmed to generate thetorque limit indicating signal for a fixed duration and then to stop toreduce the likelihood that the motor will be overpulsed.

In one embodiment, vibratory feedback is provided for the drill 100 withthe circuit shown in FIG. 31. The vibratory feedback circuit 340includes a microprocessor 342, an H-bridge driver circuit 344 and amotor interface circuit 346. Four MOSFETs 348, 350, 352 and 354 controlpower to the motor 232 from the rechargeable battery pack 106 under thecontrol of the H-bridge driver circuit 344. A shunt resistor 356 isprovided between the MOSFETs 352 and 354 and electrical ground. Thesignal at the high potential side of the resistor 356 corresponds to thetorque being generated by the motor 232. This motor torque signal isamplified by an amplifier circuit 358, which may be implemented with anoperational amplifier as shown in FIG. 31, and provided to themicrocontroller 342. The microcontroller 342 compares the motor torquesignal to the torque limit signal and generates a torque limitindicating signal in response to the motor torque signal being equal toor greater than the torque limit signal. The torque limit indicatingsignal may have a rectangular waveform.

In one embodiment, the microcontroller 342 provides a torque limitindicating signal that is a rectangular signal having an off-state of atleast 200 μseconds at a frequency of approximately 30 Hz. This torquelimit indicating signal causes the driver circuit 344 to generate motorinterface control signals that disconnect power from the motor 232 andcouple the MOSFETs 348, 350, 352 and 354 together so the current withinthe windings of the motor 232 flows back through the motor 232 todynamically brake the motor 232.

The dynamic braking causes the motor 232 to stop. Before application ofthe next on-state pulse, the microcontroller inverts the signal to thedirection control input of the H-bridge driver 344. Thus, the subsequenton-state of the rectangular pulse causes the H-bridge driver circuit 344to operate the H-bridge to couple the motor 232 to the rechargeablebattery pack 106 with a polarity that is the reverse of the one used tocouple the motor 232 and the rechargeable battery pack 106 prior tobraking. This brake/reverse/start operation of the motor at the 30 Hzfrequency causes the tool to vibrate in a manner that alerts theoperator that the torque limit has been reached while preventing the bitfrom continuing to rotate during the clutching operation. The dynamicbraking may also be used without inverting the signal.

In yet another embodiment, the rectangular waveform may be generated fora fixed duration, for example, 10 to 20 pulses, so the motor is notover-pulsed. Also, the microcontroller 342 may invert the directioncontrol signal to the H-bridge driver 344 during the off-time of therectangular waveform so that the motor 232 starts in the oppositedirection each time. This action results in the net output rotationbeing zero during the clutching duration. Additionally, themicrocontroller 342 may disable the clutching function in response tothe motor direction control signal indicating reverse, rather thanforward, operation of the motor 232.

FIGS. 32A and 32B show an embodiment of a circuit used in a tool thateliminates the need for mechanical contacts. The circuit 360 includes anoptical speed control switch 362, a two position forward/reverse switch364, a microcontroller 366, a driver circuit 368, an H-bridge circuit370, a motor 372, a shunt resistor 374, a motor torque signal amplifier376, and a torque limit signal generator 378. In this embodiment, poweris coupled to the motor 372 through the H-bridge circuit 370, but themain contact, brake contact, and bypass contact are no longer required.Thus, this embodiment significantly reduces the number of componentsthat are subject to mechanical wear and degradation. Because the opticalcontrol switch 362, microcontroller 366, driver circuit 368, H-bridgecircuit 370, and torque signal amplifier 376 may all be implemented withintegrated circuits, then ICs may be mounted on a common printed circuitand the space previously occupied by the mechanical contacts andvariable signal potentiometer are gained. This construction furtherenables the tool components to be arranged in more efficient geometries.

In the circuit 360, the optical speed control switch 362 operates asdescribed above to generate a variable control signal from thereflection of an optical signal directed at the reflective surface of apivoting trigger. The variable speed control signal is provided to themicrocontroller 366 for processing. The microcontroller 366, which maybe a microcontroller available from Texas Instruments and designated bypart number MSP430, is programmed with instructions to generate a PWMpulse with an on-state that corresponds to the level of the variablespeed signal. The microcontroller 366 provides the PWM signal to thedriver circuit 368 for generation of the four motor interface controlsignals used to couple battery power to the motor 372. The direction inwhich the motor 372 is driven is determined by the contacts in the twoposition forward/reverse switch 364 through which a signal is providedto the microcontroller 366. In the circuit 360, the contacts of the twoposition forward/reverse switch 364 do not need to carry the currentprovided to the motor 372 so the contacts of the two positionforward/reverse switch 364 may be smaller than contacts in othersystems. The directional signal is also provided by the microcontroller366 to the driver circuit 368 so the driver circuit 368 is capable oftwo directional control of current in the H-bridge circuit 370.

The motor torque signal amplifier 376 provides the torque signal fromthe high potential side of the shunt resistor 374 to the microcontroller366. The torque limit signal generator 378 may be implemented with apotentiometer as described above to provide a reference signal for themicrocontroller 366. When the microcontroller 366 determines that themotor torque signal equals or exceeds the motor torque limit, themicrocontroller 366 generates a torque limit indicating signal so thedriver circuit 368 generates the motor interface control signals thatoperate the motor 372 in a manner that causes vibration. For the TD340driver circuit, the torque limit indicating signal generated by themicrocontroller 366 is a rectangular signal having an off-state of atleast about 200 μseconds at a frequency of about 30 Hz.

While the present invention has been illustrated by the description ofexemplary processes and system components, and while the variousprocesses and components have been described in considerable detail,applicant does not intend to restrict or in any limit the scope of theappended claims to such detail. Additional advantages and modificationswill also readily appear to those skilled in the art. The invention inits broadest aspects is therefore not limited to the specific details,implementations, or illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

1. An articulating hand power tool comprising: a main housing having alongitudinal axis; a head portion rotatably engaged with the mainhousing for placement at a plurality of angles with respect to thelongitudinal axis of the main housing; an integrated circuit boardlocated within the main housing; and at least one controller accessiblefrom outside of the main housing for controlling the integrated circuitboard.
 2. The power tool of claim 1, wherein: the head portion comprisesa rotatable bit holder; the at least one controller comprises a movablereflective surface; and the integrated circuit board comprises anoptical signal generator for generating an optical signal directedtoward the reflective surface, and a speed control signal generator forgenerating a variable speed control signal that corresponds to areflection of the generated optical signal reflected by the reflectivesurface.
 3. The power tool of claim 2, wherein the moveable reflectivesurface is located on a trigger switch which extends outwardly from themain housing.
 4. The power tool of claim 3, further comprising: a fingerplatform extending from the main housing adjacent to the trigger switch.5. The power tool of claim 1, further comprising a finger platformextending from the main housing, wherein: the head portion comprises arotatable bit holder; the at least one controller comprises a buttonslidable within the finger platform between a first and a secondposition; and the integrated circuit board includes a slide switch forselecting the direction of rotation of the bit holder, the slide switchmechanically linked to the button such that when the button is movedfrom the first position to the second position the slide switch is movedfrom a third position to a fourth position.
 6. The power tool of claim1, wherein the at least one controller comprises: a first controller forcontrolling the speed of a motor housed within the main housing; and asecond controller for controlling the maximum amount of torque placedupon the motor, the first and second controller defining an axisgenerally parallel to the longitudinal axis of the main housing.
 7. Thepower tool of claim 6, wherein the integrated circuit board extendsgenerally parallel to the longitudinal axis of the main housing.
 8. Thepower tool of claim 7, wherein: the head portion is rotatable within aplane; and the at least one controller further comprises a thirdcontroller for controlling the direction of rotation of a rotatable bitholder within the head portion, wherein each of the first, the secondand the third controller lie generally in the plane.
 9. The power toolof claim 1, further comprising: a bit holder rotatably mounted in thehead portion; a motor within the main housing; and an articulating gearsystem operably coupled to the motor and the bit holder.
 10. The powertool of claim 9, further comprising: an automatic spindle lock systemwithin the head portion and coupled to the bit holder and thearticulating gear system; and a planetary gear system within the mainhousing and coupled to the motor and the articulating gear system. 11.The power tool of claim 10, wherein: the articulating gear systemcomprises a motor side pinion gear coupled to an output pinion gearthrough a bevel gear; the motor side pinion gear is coupled to theplanetary gear system and the motor side pinion gear, the planetary gearsystem and the motor are axially aligned within the main housing; andthe output pinion gear is coupled to the automatic spindle lock systemand the output pinion gear, the automatic spindle lock system and thebit holder are axially aligned with the head portion.
 12. The power toolof claim 11, wherein: the main housing defines a recess for receiving atleast a portion of a battery pack; and the integrated circuit boardextends within the main housing adjacent to the recess, the planetarygear system, and the motor.
 13. A hand power tool comprising: alongitudinally extending main housing; a head portion configured to beengaged with the main housing at a plurality of angles with respect tothe longitudinal axis of the main housing, each of the plurality ofangles within a single plane; an articulation gear system for providingmotive force to a bit holder in the head portion including a motor sidepinion gear having an axis of rotation generally parallel to alongitudinal axis of the housing and an output pinion gear having anaxis of rotation generally parallel to a longitudinal axis of the headportion, wherein the motor side pinion gear is operatively connected tothe output side pinion gear through a bevel gear; a controller operablefrom outside of the main housing and located generally on the plane; andan integrated circuit located within the main housing and responsive tothe controller.
 14. The hand power tool of claim 13, wherein thecontroller comprises a reflective surface and the integrated circuitcomprises: an optical signal generator for generating an optical signaldirected toward the reflective surface, and a speed control signalgenerator for generating a variable speed control signal thatcorresponds to a reflection of the generated optical signal reflected bythe reflective surface.
 15. The hand power tool of claim 13, wherein thecontroller comprises a clutch control and the integrated circuitcomprises: an H-bridge circuit for providing power to a motor; a linearpotentiometer for generating a motor torque limit signal; amicrocontroller for generating a dynamic braking signal in response to asignal indicative of the torque of the motor being equal to or greaterthan the torque limit signal; and a driver circuit for generatingdynamic braking signals for the H-bridge circuit corresponding to thedynamic braking signal.
 16. The hand power tool of claim 13, wherein theintegrated circuit comprises: a variable speed signal generator forcontrolling the speed of a motor; a linear potentiometer for generatinga motor torque limit signal to limit the torque of the motor; and areversing switch for controlling the direction of rotation of the motor,wherein the variable speed signal generator, the linear potentiometerand the reversing switch are located generally within the plane.
 17. Thehand power tool of claim 16, wherein the controller comprises a triggerswitch for controlling the variable speed signal generator, the triggerswitch extending from the main housing and pivotable within the plane.18. The hand power tool of claim 17, further comprising: a fingerplatform extending from the main housing and located within the planeadjacent to the trigger switch.
 19. The hand power tool of claim 18,further comprising: a button operable from outside of the main housingand extending within the finger platform, the button operably connectedto the reversing switch for controlling the position of the reversingswitch.
 20. A method of operating a hand power tool comprising: rotatinga head portion of the power tool to one of a plurality of angles withrespect to the longitudinal axis of a main housing of the power tool;moving a variable speed trigger switch located outside of the mainhousing; generating a variable speed signal with an integrated circuitlocated within the main housing in response to the movement of thevariable speed trigger; controlling the speed of a motor located withinthe main housing based upon the variable speed signal; and transferringmotive force from the motor to a component within the head portion. 21.The method of claim 20, wherein transferring motive force from the motorto a component within the head portion comprises: rotating a firstpinion gear using the motor; rotating a bevel gear using the firstpinion gear; rotating a second pinion gear using the bevel gear; androtating a bit holder within the head portion using the second piniongear.
 22. The method of claim 21, further comprising: positioning aclutch control located outside of the housing; and generating a motortorque limit signal based upon the position of the clutch control usingthe integrated circuit, wherein controlling the speed of the motorcomprises controlling the speed of the motor based upon the torque limitsignal.
 23. The method of claim 22, further comprising: positioning areversing control located outside of the housing; generating a motordirection signal based upon the position of the reversing control usingthe integrated circuit; and controlling the direction of rotation of themotor based upon the motor direction signal.
 24. The method of claim 20,wherein rotating the head portion of the power tool comprises:disengaging a plurality of teeth on an articulation button from aplurality of teeth in the main housing while the head portion is in afirst position; rotating the articulation button with the head portionfrom the first position to a second position; and engaging the pluralityof teeth on the articulation button with the plurality of teeth on themain housing while the head portion is in the second position.